1. Field of the Invention
The present invention relates to a liquid ejection head for ejecting a liquid.
2. Description of the Related Art
In an ink jet recording apparatus, information is recorded on a recording medium by ejecting ink from a plurality of fine nozzles of a recording head in accordance with a recording signal. The ink jet recording apparatus is generally and widely employed because of having advantages such as high-speed recording, high resolution, high image quality, and low noise.
A recording head used in the ink jet recording apparatus is, for example, of the ink jet type recording an image with utilization of thermal energy. In the recording head of the ink jet type, information is recorded by supplying a current to a recording element to heat ink such that the ink is ejected through an ejection orifice under pressure produced upon generation of bubbles. The ink ejected through the ejection orifice is caused to fly in a direction perpendicular to a principal surface of a recording element substrate and to land at a desired position on a recording medium. As a result, the recording with high image quality and high definition is realized.
Japanese Patent Laid-Open No. 2010-201921 describes an ink jet recording head in which pressure chambers for ejecting ink and ink supply ports are adjacently arrayed in a direction in which nozzles are arrayed. FIG. 2 of Japanese Patent Laid-Open No. 2010-201921 is an enlarged view of a nozzle array. A plurality of electrothermal transducers 6 and a plurality of ink supply ports 2A are alternately arrayed in the nozzle array direction. FIG. 3 of Japanese Patent Laid-Open No. 2010-201921 is a sectional view taken along a line III-III in FIG. 2. An ejection orifice 7 is formed in an orifice plate 3 at a position opposed to each of the electrothermal transducers 6. In FIGS. 2 and 3 of Japanese Patent Laid-Open No. 2010-201921, a pressure chamber R is formed between the electrothermal transducer 6 and the orifice plate 3, and the ink supply port 2A is formed adjacent to the pressure chamber. Because the ink supply port having an opening of a larger size than the electrothermal transducer is formed near the pressure chamber, flow resistance can be reduced when the ink is refilled into the pressure chamber. As a result, high-speed printing can be performed by increasing an ink ejection frequency. Furthermore, with the arrangement that the ink supply port having the opening width set described above is arranged adjacent to the pressure chamber in the array direction of the electrothermal transducers (heating resistors), the ink supply port can effectively absorb pressure in the pressure chamber, thus reducing the so-called crosstalk between the adjacent the pressure chambers.
As a method of forming the ink supply port, which has the predetermined size, near the pressure chamber with high accuracy, U.S. Pat. No. 6,534,247 describes a two-step etching process performed on a silicon substrate. According to a method of manufacturing an ink jet recording head, described in U.S. Pat. No. 6,534,247 with reference to FIGS. 5a to 6c, an independent supply port (called “ink feed channel” in the U.S. patent) is first formed from a front surface of the substrate by, e.g., dry etching. Next, a recess is formed by performing wet etching, as first etching, on the silicon substrate, thus forming a liquid chamber (FIG. 5b of U.S. Pat. No. 6,534,247). Next, a slit-shaped pattern is formed in the bottom surface of the recess, and second etching is performed on the bottom surface of the recess along the slit-shaped pattern by silicon dry etching. As a result, the recess is communicated with the independent supply port, which has been formed in advance, whereby the ink jet recording head is completed (FIG. 6b of U.S. Pat. No. 6,534,247). Thus, according to the method of manufacturing an ink jet recording head, described in U.S. Pat. No. 6,534,247, the independent supply port having the same size as a heater size is formed from the front surface of the substrate. A tilting phenomenon (i.e., a deviation in directionality) due to distortion of a plasma sheath does not occur. Moreover, in the event of the distortion of the plasma sheath when the slit-shaped pattern is formed from the rear side of the substrate, ejection characteristics of the ink jet recording head are not affected because it is just requited to establish the communication between the recess and the independent supply port. For that reason, U.S. Pat. No. 6,534,247 describes neither the influence of a plasma molding effect, nor the distortion of the plasma sheath.